Add Rails dependency

Author: gshaw

concise_logging.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "rails", ">= 3.0"
+  spec.add_runtime_dependency "rails", "~> 4.1"
 
   spec.add_development_dependency "bundler", "~> 1.7"
   spec.add_development_dependency "rake", "~> 10.0"